Another balun question... this one for HF

[wbswetnam]

For HF work, I recently bought an end-fed 6m - 40m multiband antenna from Honolulu EARC (Emergency Amateur Radio Club - Hawaii) which features a 9:1 UNUN at the end of a 30' vertically-mounted longwire. In addition to (somewhat) matching the high impedence of the antenna, will it also serve double duty to prevent RF from coming back into the shack from the antenna, like the 1:1 balun?

I understand that I'll have to use an outboard antenna matcher for this antenna, the Yaesu 857D's internal antenna matcher is not likely to be able to match it very effectively. Thanks!

 

[wbswetnam]

No responses... I'm going to assume that the answer to my question is 'yes'.

 

[prcguy]

The 9:1 balun will reduce some current on the feedline and it depends on antenna wire length, frequency, etc. The EARC and all 9:1 balun antennas with random/non resonant lengths of wire can be quite a compromise, especially on the lower bands. With 30ft of wire don't expect any glowing reports on 40 or 80m.

If you have the space you can make an end fed resonant half wave that will operate on harmonically related bands. A 40m version will also work great on 20 and 10m and its about 65ft long. You can make a 100w version for less than $10 plus wire and a 600-800w version for about $30 plus wire.
prcguy

 

[supercazzola]

@prcguy, do you have a URL with those instructions?

 

[prcguy]

Here are 3 sites with a common theme, 2 turn primary and 14 turn secondary with a 150pf cap across the input. The primary is a twisted pair with the secondary.

PD7MAA HOMEPAGE: Multiband end fed antennas 3.5 - 30mHz

https://forums.hamisland.net/showthread.php/21993-The-multi-band-end-fed-antenna-with-a-twist?

Multi/Any band end-fed (English) | PA3HHO

For a 100w version use an FT-114A-43 core and for 600-800w use two stacked FT-240-43 cores, all available here: 43 Material Ferrite Toroids

With about 65ft of wire these transformers will match and give you 40, 20 and 10m with great performance, basically the same as using a center fed 40m dipole with balanced line to a tuner. The larger stacked core version works fine down to 80m with about 135ft of wire but if tuned for the upper phone portion of 80m it will resonate above 40, 20, 10 and other bands, so I make a 40m version with an insulator at the end then add the extra wire and jumper to the 40m section to resonate on 80m and remove the jumper for the higher bands. For 60m use about 88ft of wire and it might also resonate on 30m and 15m.

I use a 100w version several times a week in local parks with a KX3. The 65ft of wire and about 40ft of guy string wind up into a plastic chalk line reel which also serves as the throw weight to get one end up into the trees. I also carry a second chalk line reel with about 80ft of guy string to raise the transformer end whenever possible. I also use about 25ft of miniature RG-316 or LMR-100 coax and the entire antenna with coax is very lightweight for travel.

Amway, hope you make one and compare to the EARC antenna, you should be pleasantly surprised with the performance.
prcguy

@prcguy, do you have a URL with those instructions?